Slab pies are one of my favorite things to make for a large crowds. You can cut the pie into smaller pieces, meaning it an easily serve a bunch of people. And because there is less filling, it also one of those pies that are perfect for crust lovers as the ratio of crust to filling is higher. If you want, you can make the crust ahead by a day and let it chill overnight in the fridge. I make this crust with oats, which has that whole grain goodness that goes so well with the rhubarb, blueberries and strawberries. It’s almost like eating breakfast for dessert!
Course Dessert
Cuisine American
Prep Time 30 minutesminutes
Cook Time 1 hourhour
Total Time 1 hourhour30 minutesminutes
Servings 12
Calories 450kcal
Author Irvin
Ingredients
Crust
2cupsall-purpose flour280 g
1cupwhite whole wheat flour150 g
1 1/2cupsquick cook or baby rolled oats150 g
1teaspoonkosher salt
1 1/2cupsunsalted butter340 g or 3 sticks
3/4cupcold waterplus an additional 1/4 cup if necessary
Filling
3cupshalved strawberries455 g or 1 lb
2cupsblueberries300 g or 10 1/2 oz
3/4cupgranulated sugardivided, 150 g
1/4cupcornstarch35 g
Zest of 1 lemon
1/4teaspoonkosher salt
1/4teaspoonfresh ground pepper
5cups1/2-inch chopped rhubarb625 g or 1 lb 6 oz
1teaspoonbalsamic vinegar
To assemble
1large egg
1tablespooncold water
2tablespoonTurbinado sugaror white sugar
Instructions
Make the crust.
Place the flours, oats, and salt in a large bowl. Stir with a whisk. Cut the butter into 1/2-inch chunks. Sprinkle over the dry ingredients and toss to coat. Using your fingers, press and smash the cubes into small bits, about the size of peas (but flat, not round). Sprinkle 3/4 cup of water into the bowl and stir with a fork until it starts to get shaggy. Sprinkle more water, a tablespoon at a time, if the dough looks too dry.
Once the dough starts to look shaggy, start to massage it with the palms of your hand to incorporate the dry ingredients. Divide in half, pat into a 1-inch thick disk. Cover with plastic wrap and chill in the refrigerator 1 hour or overnight.
Make the filling.
Once the dough is chilled, place the strawberries, blueberries, 1/2 cup sugar, cornstarch, lemon zest, salt and pepper in a large mixing bowl. Fold together and set aside.
Place rhubarb and remaining 1/4 cup of sugar in a large saute pan and cook on high, stirring constantly, until the sugar has dissolved, and the rhubarb has released liquid. Lower the heat to medium and cook the rhubarb until some of the liquid has evaporated, but the rhubarb still holds it shape and is firm. Remove from heat and pour rhubarb and any remaining liquid into the bowl with the berries. Add the balsamic vinegar and fold filling together.
Assemble the pie.
Preheat the oven to 400°F. Lightly and evenly spray a 9 x 13 x 2-inch metal pan with a cooking oil. If using, cut a piece of parchment paper large enough to fit into the metal pan with a good 2” hanging over the edge of the pan on either side of the long edge. Fit the parchment paper into the metal pan; the cooking oil should help anchor the paper to the pan.
On a well-floured surface, roll out one disc of the pie crust to a rectangle that is 15” by 11” in length. Carefully transfer it to the metal pan, with the sides of the crust going up all sides of the pan with an inch overhang. Carefully spoon in the pie filling into the middle of the pan, spreading the filling all the way around, and lifting the sides of the crust if they have fallen down, so that the filling is “inside” the crust. Once you added all the filling and evenly distributed around the pan, it should hold the sides of the pie crust up.
Roll out the second disc of pie crust to a 15” by 11” rectangle. Either cut the second crust into strips and “weave” a top similar to the classic apple pie or transfer the whole top crust to the pan, and tuck the edges of the dough into the side of the pan, on top of the bottom crust. Pinch the top edge of the pie all the way around to seal the pie crust, and then cut the top of the pie with a knife decoratively to give some steam vents.
Take the egg and water and beat them together with a fork until it starts to froth. Brush the top of the pie crust with the egg wash and then sprinkle the turbinado or white sugar on top.
Place pan on a rimmed baking sheet and bake in oven for 55 to 65 minutes, or until the filling is bubbling through the top crust holes or vents and the top of the crust is golden brown. If the crust is browning too fast and the filling isn’t bubbling yet, cover with aluminum foil to keep the top crust from burning.
Notes
Note: If you don’t have quick cook or baby rolled oats, place the same amount of regular or thick cut oats in a food processor or blender, and pulse until the oats have broken down into the size of tiny pebbles.